This afternoon while cleaning a closet I pulled out an old US map that had
been marked with contacts I made back when I worked 10M a lot. After the
local stations there is a big empty area on the map then I started making
contacts again at about 300 miles. Antenna used was a 1/4 lambda groundplane
with the radials drooping so to match 50 ohms. A chart I found indicates
that this means I have a vertical angle of radiation of 50 to 60 degrees. Is
this correct??. I didnt think the angle would be so great for this antenna.

BTW the antenna was about 30 ft off the ground when in use.
Jimmie

"Jimmie D" wrote in message
...
This afternoon while cleaning a closet I pulled out an old US map that had
been marked with contacts I made back when I worked 10M a lot. After the
local stations there is a big empty area on the map then I started making
contacts again at about 300 miles. Antenna used was a 1/4 lambda
groundplane
with the radials drooping so to match 50 ohms. A chart I found indicates
that this means I have a vertical angle of radiation of 50 to 60 degrees.
Is
this correct??. I didnt think the angle would be so great for this
antenna.

The gap between the farthest of the ground wave contacts and the nearest of
the skip contacts is termed the Skip Zone and the 50 to 60 degree number you
cited sounds accurate. It represents the highest takeoff angle that is
successfully refracted back to earth.

Please note there is no one takeoff angle. It's a range of angles and your
transmissions at many angles are returned simultaneously. A quoted takeoff
angle is merely the angle for the strongest signal. For a given paths a
particular takeoff angle may be optimum, but others will still work.

On Tue, 12 Dec 2006 22:18:42 -0500, "Jimmie D"
wrote:

This afternoon while cleaning a closet I pulled out an old US map that had
been marked with contacts I made back when I worked 10M a lot. After the
local stations there is a big empty area on the map then I started making
contacts again at about 300 miles. Antenna used was a 1/4 lambda groundplane
with the radials drooping so to match 50 ohms. A chart I found indicates
that this means I have a vertical angle of radiation of 50 to 60 degrees. Is
this correct??. I didnt think the angle would be so great for this antenna.

BTW the antenna was about 30 ft off the ground when in use.
Jimmie


Would the skip zone (the gap between where ground wave peters out and
where sky wave is sufficiently low angle to refract in the ionosphere)
explain your observation?

Owen
--

"Owen Duffy" wrote in message
...
On Tue, 12 Dec 2006 22:18:42 -0500, "Jimmie D"
wrote:

This afternoon while cleaning a closet I pulled out an old US map that had
been marked with contacts I made back when I worked 10M a lot. After the
local stations there is a big empty area on the map then I started making
contacts again at about 300 miles. Antenna used was a 1/4 lambda
groundplane
with the radials drooping so to match 50 ohms. A chart I found indicates
that this means I have a vertical angle of radiation of 50 to 60 degrees.
Is
this correct??. I didnt think the angle would be so great for this
antenna.

BTW the antenna was about 30 ft off the ground when in use.
Jimmie


Would the skip zone (the gap between where ground wave peters out and
where sky wave is sufficiently low angle to refract in the ionosphere)
explain your observation?

Owen
--

Yes but the chart I have seems to be telling me that the distance to the
first skip zone has a direct correlation with radiation angle with 300 miles
being indicated for an antenna with a 50 or 60 degree angle . Is this
correct? I was thinking this particular antenna would have a lower radiation
angle but I am beginning to think this may be typical of the drooping radial
1/4 wl antena.

"Sal M. Onella" wrote in message
...

"Jimmie D" wrote in message
...
This afternoon while cleaning a closet I pulled out an old US map that
had
been marked with contacts I made back when I worked 10M a lot. After the
local stations there is a big empty area on the map then I started making
contacts again at about 300 miles. Antenna used was a 1/4 lambda
groundplane
with the radials drooping so to match 50 ohms. A chart I found indicates
that this means I have a vertical angle of radiation of 50 to 60 degrees.
Is
this correct??. I didnt think the angle would be so great for this
antenna.

The gap between the farthest of the ground wave contacts and the nearest
of
the skip contacts is termed the Skip Zone and the 50 to 60 degree number
you
cited sounds accurate. It represents the highest takeoff angle that is
successfully refracted back to earth.

Please note there is no one takeoff angle. It's a range of angles and
your
transmissions at many angles are returned simultaneously. A quoted
takeoff
angle is merely the angle for the strongest signal. For a given paths a
particular takeoff angle may be optimum, but others will still work.



Makes sense, since as I get further away, 600 miles the density of contacts
actually increases.
Seems to be a really strong concentration of contacts in gulf area from
louisianna on toward
texas from here in north carolina.

On Tue, 12 Dec 2006 23:45:42 -0500, "Jimmie D"
wrote:


"Owen Duffy" wrote in message
.. .
On Tue, 12 Dec 2006 22:18:42 -0500, "Jimmie D"
wrote:

This afternoon while cleaning a closet I pulled out an old US map that had
been marked with contacts I made back when I worked 10M a lot. After the
local stations there is a big empty area on the map then I started making
contacts again at about 300 miles. Antenna used was a 1/4 lambda
groundplane
with the radials drooping so to match 50 ohms. A chart I found indicates
that this means I have a vertical angle of radiation of 50 to 60 degrees.
Is
this correct??. I didnt think the angle would be so great for this
antenna.

BTW the antenna was about 30 ft off the ground when in use.
Jimmie


Would the skip zone (the gap between where ground wave peters out and
where sky wave is sufficiently low angle to refract in the ionosphere)
explain your observation?

Owen
--

Yes but the chart I have seems to be telling me that the distance to the
first skip zone has a direct correlation with radiation angle with 300 miles
being indicated for an antenna with a 50 or 60 degree angle . Is this
correct? I was thinking this particular antenna would have a lower radiation
angle but I am beginning to think this may be typical of the drooping radial
1/4 wl antena.


J,

If I treat the earth as flat, and figure that the propagation is via
F2 layer, say at virtual height 300km, the the rise is 300km for a run
of half of 300mi, or 240km, so the angle of departure is 51 deg.

The refraction mechanism is sharp cut-off, higher angle of incidence
will not refract.

We don't know what the pattern on your antenna is, but even though it
may have some sharp deep nulls, it is most unlikely to exhibit a total
cutoff above that 50 to 60 degree number you have proposed.

Antenna patterns influence things, but exceeding the MUF on a path
assures you of no propagation, the MUF dominates. Sure the MUF varies
over time, but your historical observations probably just capture the
highest MUF that occured with some small probability, depending on how
much time you put in to collecting the QSOs.

Owen
--

On Tue, 12 Dec 2006 23:45:42 -0500, "Jimmie D"
wrote:

I was thinking this particular antenna would have a lower radiation
angle

is unrelated to:

but I am beginning to think this may be typical of the drooping radial
1/4 wl antena.

Hi Jimmie,

The drooping radials affect match only (classically so). The relation
of the WHOLE antenna to ground is the significant predictor of
radiation angle.

73's
Richard Clark, KB7QHC

Richard Clark wrote:
On Tue, 12 Dec 2006 23:45:42 -0500, "Jimmie D"
wrote:

I was thinking this particular antenna would have a lower radiation
angle

is unrelated to:

but I am beginning to think this may be typical of the drooping radial
1/4 wl antena.

Hi Jimmie,

The drooping radials affect match only (classically so). The relation
of the WHOLE antenna to ground is the significant predictor of
radiation angle.

73's
Richard Clark, KB7QHC

Hello Richard,

The quarter-wave ground-plane antenna's vertical radiation pattern
approaches that of a half-wave vertical as the radial droop approaches
90 degrees, while the feedpoint height remains fixed. Whether one views
that as significant is subjective, of course.

73,

Chuck, NT3G

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Jimmie D wrote:
This afternoon while cleaning a closet I pulled out an old US map that had
been marked with contacts I made back when I worked 10M a lot. After the
local stations there is a big empty area on the map then I started making
contacts again at about 300 miles. Antenna used was a 1/4 lambda groundplane
with the radials drooping so to match 50 ohms. A chart I found indicates
that this means I have a vertical angle of radiation of 50 to 60 degrees. Is
this correct??. I didnt think the angle would be so great for this antenna.

Every antenna has a vertical beam width. For Vert1.ez
that comes with EZNEC, the 3 dB vertical beamwidth
goes from 9 deg to 53 deg with maximum radiation occurring
at 26 degrees. The vertical beamwidth on a vertical
creates a doughnut of coverage for the first hop. The
inner circle of your doughnut was at 300 miles where
your radiated power may have been more than 3 dB down
from your angle of maximum gain. Question is: Where
was the outer circle of your first hop doughnut?
--
73, Cecil http://www.w5dxp.com

Jimmie D wrote:

This afternoon while cleaning a closet I pulled out an old US map that had
been marked with contacts I made back when I worked 10M a lot. After the
local stations there is a big empty area on the map then I started making
contacts again at about 300 miles. Antenna used was a 1/4 lambda groundplane
with the radials drooping so to match 50 ohms. A chart I found indicates
that this means I have a vertical angle of radiation of 50 to 60 degrees. Is
this correct??. I didnt think the angle would be so great for this antenna.

BTW the antenna was about 30 ft off the ground when in use.
Jimmie



What is missing is the altitude of the reflecting zone. The altitude of the E,
F1, F2 layers very greatly depending on solar activity, season and time of day.
There are so many variables in propagation that is is impossible to definitely
state what the path and angle were.